20231999 has 4 divisors (see below), whose sum is σ = 20343960. Its totient is φ = 20120040.

The previous prime is 20231987. The next prime is 20232001. The reversal of 20231999 is 99913202.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20231999 - 2¹⁶ = 20166463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20231909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55709 + ... + 56070.

It is an arithmetic number, because the mean of its divisors is an integer number (5085990).

Almost surely, 2^20231999 is an apocalyptic number.

20231999 is a deficient number, since it is larger than the sum of its proper divisors (111961).

20231999 is a wasteful number, since it uses less digits than its factorization.

20231999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111960.

The product of its (nonzero) digits is 8748, while the sum is 35.

The square root of 20231999 is about 4497.9994441974. Note that the first 3 decimals coincide. The cubic root of 20231999 is about 272.4872995792.

The spelling of 20231999 in words is "twenty million, two hundred thirty-one thousand, nine hundred ninety-nine".